/**
* Copyright 2010 JBoss Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.drools.planner.core.localsearch.termination;
import org.drools.planner.core.localsearch.StepScope;
/**
* @author Geoffrey De Smet
*/
public class UnimprovedStepCountTermination extends AbstractTermination {
private int maximumUnimprovedStepCount = 100;
public void setMaximumUnimprovedStepCount(int maximumUnimprovedStepCount) {
this.maximumUnimprovedStepCount = maximumUnimprovedStepCount;
if (maximumUnimprovedStepCount < 0) {
throw new IllegalArgumentException("Property maximumUnimprovedStepCount (" + maximumUnimprovedStepCount
+ ") must be greater or equal to 0.");
}
}
// ************************************************************************
// Worker methods
// ************************************************************************
private int calculateUnimprovedStepCount(StepScope stepScope) {
int bestStepIndex = stepScope.getLocalSearchSolverScope().getBestSolutionStepIndex();
int stepIndex = stepScope.getStepIndex();
return stepIndex - bestStepIndex;
}
public boolean isTerminated(StepScope stepScope) {
int unimprovedStepCount = calculateUnimprovedStepCount(stepScope);
return unimprovedStepCount >= maximumUnimprovedStepCount;
}
public double calculateTimeGradient(StepScope stepScope) {
int unimprovedStepCount = calculateUnimprovedStepCount(stepScope);
double timeGradient = ((double) unimprovedStepCount) / ((double) maximumUnimprovedStepCount);
return Math.min(timeGradient, 1.0);
}
}